Air Conditioning System (Diagnostics - Introduction): Overview Lexus GX J150

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1. IF ANY OF FOLLOWING CONDITIONS ARE MET, KEEP ENGINE IDLING (ENGINE SPEED AT LESS THAN 2000 RPM) WITH AIR CONDITIONING SWITCH ON FOR AT LEAST 2 MINUTES Refrigerant gas has been refilled or parts of the air conditioning system have been replaced. The engine has not been started for a long time. NOTE: If the engine speed is more than 2000 rpm, the cooler compressor assembly may be damaged.
2. DO NOT HANDLE REFRIGERANT IN AN ENCLOSED AREA OR NEAR AN OPEN FLAME
3. ALWAYS WEAR EYE PROTECTION
4. BE CAREFUL NOT TO GET LIQUID REFRIGERANT IN YOUR EYES OR ON YOUR SKIN If liquid refrigerant gets in your eyes or on your skin: Wash the area with lots of cold water. WARNING: Do not rub your eyes or skin. Apply clean petroleum jelly to the skin. Go immediately to a hospital or see a physician for professional treatment.
5. NEVER HEAT CONTAINER OR EXPOSE IT TO OPEN FLAME
6. BE CAREFUL NOT TO DROP CONTAINER OR APPLY PHYSICAL SHOCKS TO IT
7. DO NOT OPERATE COMPRESSOR WITH INSUFFICIENT REFRIGERANT IN REFRIGERANT SYSTEM If there is not enough refrigerant in the refrigerant system, oil lubrication will be insufficient and compressor burnout may occur. Necessary care should be taken to avoid this.
8. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE WHILE COMPRESSOR IS OPERATING Open and close only the low pressure valve. Opening and closing the high pressure valve could cause the charging cylinder to rupture. TEXT IN ILLUSTRATION *a INCORRECT *b CORRECT
9. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH REFRIGERANT If the refrigerant is overcharged, it causes problems such as insufficient cooling, poor fuel economy and engine overheating.
10. DO NOT OPERATE ENGINE AND COOLER COMPRESSOR ASSEMBLY WITHOUT REFRIGERANT NOTE: This may damage the inside of the cooler compressor assembly.

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COMMUNICATION TABLE

1. *1: w/ Navigation System
2. *2: w/o Navigation System
3. *3: w/ Rear Air Conditioning System

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1. GENERAL The air conditioning system has the following controls. Control Outline Neural Network Control This control is capable of performing complex control by artificially simulating the information processing method of the nervous system of living organisms in order to establish a complex input/output relationship similar to that of a human brain. Automatic Recirculation Control Automatically changes the air inlet mode to the fresh air or recirculation air mode according to the level of harmful elements in the outside air, cabin temperature, and outside temperature. Outlet Air Temperature Control Based on the temperature set by the temperature control dial, neural network control calculates outlet air temperature based on input signals from various sensors. Pollen Removal Mode Control When the pollen removal mode switch is pressed, pollen removal mode control is activated and the air vent is switched to the FACE mode. Sends air, which is filtered by the clean air filter to remove pollen, to the area around the upper parts of the bodies of the driver and front passenger. Left and Right Independent Control The temperature settings for the driver and front passenger are controlled independently in order to provide separate vehicle interior temperatures for the right and left sides of the vehicle. Blower Control Controls the blower motor in accordance with the airflow volume that has been calculated by neural network control based on the input signals from various sensors. Air Outlet Control Automatically switches the air outlets in accordance with the outlet mode that has been calculated by neural network control. In accordance with the engine coolant temperature, ambient air temperature, amount of sunlight, required blower speed, outlet temperature and vehicle speed conditions, this control automatically switches the blower outlet to foot and defroster mode to prevent the windows from becoming fogged up when the ambient air temperature is low. Air Inlet Control Automatically controls the air inlet control damper to help achieve the calculated outlet air temperature that is required. Drives the air inlet control servo motor according to the operation of the air inlet control switch and moves the dampers to the fresh or recirculation position. Compressor Control The air conditioning amplifier assembly compares the A/C pulley speed signals, which are transmitted by the ECM (crankshaft position sensor). When the air conditioning amplifier assembly determines that the A/C pulley is locked, it turns off the magnet clutch assembly. Defroster Control Defroster control logic is used to improve defroster performance. Rear Defogger Control When the engine switch is on (IG) and the rear defogger switch is pushed, the system is activated to keep the defogger heater on for approx. 15 minutes. However, the operating time of the rear defogger can be extended up to approx. 255 minutes when both of the following requirements are met: Ambient Temperature: -3°C (26.6°F) or less Vehicle Speed: 50 km/h (31.1 mph) or more Memory Call Control Memorizes the last front and rear air conditioning settings when the engine switch is turned from on (IG) to off in accordance with the ID code of the key that is used to operate the vehicle. The key-linked memory call control then recalls the settings if the key is used when the engine switch on (IG). This function operates when both of the following conditions are met: Inside of the outside door handle is touched or the driver door is unlocked using the unlock button, and then the driver door is opened. Engine switch on (IG). Diagnosis A Diagnostic Trouble Code (DTC) is stored in memory when the air conditioning amplifier assembly detects a problem with the air conditioning system.
2. NEURAL NETWORK CONTROL Neural network control collects data under varying environmental conditions and stores it in the air conditioning amplifier assembly. Neural network control uses this data to enhance air conditioning control. Neural network control consists of neurons organized into an input layer, intermediate layer and output layer. The input layer neurons process the input data received from the switches and sensors, which includes the outside temperature, amount of sunlight and room temperature, and outputs this data to the intermediate layer neurons. Based on this data, the intermediate layer neurons adjust the strength of the links among the neurons. The result is then calculated by the output layer neurons in the form of the required outlet temperature, solar correction, target airflow volume and outlet mode control volume. The air conditioning amplifier assembly then controls the servo motors and blower motor in accordance with the control volumes that have been calculated by neural network control.
3. AUTOMATIC RECIRCULATION CONTROL (w/ Rear Air Conditioning System) When the automatic recirculation control is operating, the air conditioning amplifier assembly automatically changes the air inlet mode to the fresh air or recirculate air mode based on signals from the smog ventilation sensor, ambient temperature and room temperature sensors when the AUTO air inlet mode is selected. The air conditioning amplifier assembly detects harmful elements (CO, HC, and NOx) based on a smog ventilation sensor signal and automatically switches the air inlet mode to the recirculate air mode to prevent such harmful elements from entering the cabin. The air conditioning amplifier assembly detects cabin temperature based on a room temperature sensor signal and automatically switches the air inlet mode to the recirculate air mode to cool down the cabin temperature quickly. The air conditioning amplifier assembly detects the outside temperature based on an ambient temperature sensor signal and automatically switches the air inlet mode to the fresh air mode to prevent the windshield from fogging up. NOTE: The smog ventilation sensor cannot detect elements such as the smoke from a bonfire or factory exhaust, foul or animal odors, and dirt or dust particles. Therefore, the air inlet mode is not switched automatically in accordance with those elements.
4. MEMORY CALL CONTROL Memory call control memorizes the air conditioning system settings together with the ID code of the key that is being used. When a key with memory is used to unlock the door, while the driver door is opened and the engine switch is turned on (IG), the memorized air conditioning system settings will be recalled. The certification ECU will recognize the key during the unlock operation by reading the registered ID code. Using this control, the air conditioning system setting preference that corresponds to each key can be memorized, enhancing usability. The following air conditioning system settings can be memorized: FRONT AIR CONDITIONING UNIT Setting Condition A/C Switch On or Off AUTO Switch On or Off Temperature Setting Driver Side LO, 18 to 32°C (65 to 85°F) or HI Front Passenger Side LO, 18 to 32°C (65 to 85°F) or HI Blower Fan Speed Level 1 to 7 Air Inlet Mode Fresh or Recirculate Air Outlet Mode Face, Bi-Level, Foot, Foot/Defroster or Defroster REAR Switch*1 DUAL Switch*2 On or Off REAR AIR CONDITIONING UNIT (W/ REAR AIR CONDITIONING SYSTEM) Setting Condition AUTO Switch On or Off Temperature Setting LO, 18 to 32°C (65 to 85°F) or HI Blower Fan Speed Level 1 to 7 Air Outlet Mode Face, Bi-Level or Foot *1: w/ Navigation System *2: w/o Navigation System
5. POLLEN REMOVAL MODE CONTROL When the pollen removal mode switch is pressed, the pollen removal mode control is activated. Then, the air vent is switched to the FACE mode and recirculated pollen free air flows in the area around the upper parts of the bodies of the driver and front passenger. When the pollen removal mode switch signal is input to the air conditioning amplifier assembly, the air conditioning amplifier assembly controls the magnet clutch assembly, recirculation damper servo sub-assembly, No. 1 air conditioning radiator damper servo sub-assembly (mode damper servo) and blower with fan motor sub-assembly as shown in the timing chart. This control usually operates for approximately 3 minutes. After this control stops operating, the air conditioning amplifier assembly automatically returns to the mode it was in just before the pollen removal mode switch was pressed.
6. MODE POSITION AND DAMPER OPERATION Mode Position and Damper Operation Front Air Conditioning Unit FUNCTION OF MAIN DAMPER Control Damper Operation Position Damper Position Operation Air Inlet Control Damper Fresh A Brings in fresh air. Recirculation B Recirculates internal air. Air Mix Control Damper MAX COOL to MAX HOT E - D - C E' - D' - C' Varies the mixture of cold air and hot air in order to regulate the temperature continuously from hot to cool. MAX COOL Damper MAX COOL V Open in the MAX COOL position. Except MAX COOL W Close in all position except MAX COOL position. MAX HOT Damper MAX HOT Y Open in the MAX HOT position. Except MAX HOT X Closed in all position except MAX HOT position. Mode Control Damper Face F, I, N, T, X (FACE 1) F, J, N, T, X (FACE 2) Air blows out of the front center registers, side registers and rear face registers. (FACE 1) Air blows out of the front center registers, side registers and rear face registers. In addition, air blows out slightly from the front and rear footwell register ducts. (FACE 2) Bi-level G, L, N, T, X Air blows out of the front center registers, side registers, rear face registers and front and rear footwell register ducts. Foot H, M, P, T, W, Y (MAX HOT position) H, M, O, T, X (Except MAX HOT Position) Air blows out of the front and rear footwell register ducts. In addition, air blows out slightly from the front defroster, side defroster, side registers, front center registers and rear face registers. Foot/Def H, K, R, T, W, Y (MAX HOT position) H, M, Q, T, X (Except MAX HOT Position) Defrosts the windshield through the front defroster, side defroster and side registers while air is also blown out from the front and rear footwell register ducts. In addition, air blows out slightly from the front center registers and rear face registers. Def H, I, S, U, X Defrosts the windshield through the front defroster and side defroster. Rear Air Conditioning Unit (w/ Rear Air Conditioning System) FUNCTION OF MAIN DAMPER Control Damper Operation Position Damper Position Operation Mode Control Damper Face A Air blows out from the rear roof registers. Bi-level B Air blows out from the rear roof registers and rear side registers. Foot C Air blows out from the rear side registers. Air Mix Control Damper MAX COLD to MAX HOT Temperature Setting D, E Varies the mixture of cold air and hot air in order to regulate the temperature continuously from hot to cold.
7. AIR OUTLETS AND AIRFLOW VOLUME Air Outlets and Airflow Volume for Front Registers Indication (Mode) Front Center Register Side Register Front Footwell Register Rear Face Register* Rear Footwell Register Front Defroster Side Defroster A B C D E F G Face 1 - - - - Face 2 - - Bi-level - - Foot Foot/Def Def - - - - - *: w/o Rear Air Conditioning System HINT: The size of the circle indicates the proportion of airflow volume. for Rear Registers (w/ Rear Air Conditioning System) Indication (Mode) Rear Roof Register Rear Side Register A B Face - Bi-level Foot - HINT: The size of the circle o indicates the ratio of airflow volume.
8. A/C LOCK SENSOR The A/C lock sensor sends A/C pulley speed signals to the air conditioning amplifier assembly. The air conditioning amplifier assembly determines whether the cooler compressor assembly is locked or not by using those signals and engine speed signals.
9. No. 1 COOLER THERMISTOR The No. 1 cooler thermistor detects the temperature of the cool air immediately after it passes through the evaporator in the form of resistance changes, and outputs the temperature to the air conditioning amplifier assembly.
10. BLOWER WITH FAN MOTOR SUB-ASSEMBLY The blower with fan motor sub-assembly has a built-in blower controller and is controlled by the air conditioning amplifier assembly using duty control.
11. AIR CONDITIONING HARNESS ASSEMBLY (BUS CONNECTOR) A BUS connector is used in the wire harness that connects the servo motor to the air conditioning amplifier assembly. Connector Type Connected to *1: Bus connector No. 1 air conditioning radiator damper servo sub-assembly (driver side air mix damper servo) *2: Bus connector No. 1 air conditioning radiator damper servo sub-assembly (mode damper servo) *3: Bus connector No. 2 air conditioning radiator damper servo sub-assembly (front passenger side air mix damper servo) *4: Bus connector Recirculation damper servo sub-assembly *5: Connector Air conditioning amplifier assembly *6: Connector No. 1 cooler thermistor Each BUS connector has a built-in communication/driver IC which communicates with each servo motor connector, actuates the servo motor, and has a position detection function.
12. SERVO MOTOR The pulse pattern type servo motor detects the relative position using 2-bit on/off signals. The forward and reverse revolutions of this motor are detected using two signals, A and B, which output four types of patterns. The air conditioning amplifier assembly counts the number of pulse patterns in order to determine the stopped position.
13. COOLER THERMISTOR (ROOM TEMPERATURE SENSOR) The cooler thermistor (room temperature sensor) detects the cabin temperature based on changes in the resistance of its built-in thermistor and sends a signal to the air conditioning amplifier assembly.
14. COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR) The cooler thermistor (ambient temperature sensor) detects the outside temperature based on changes in the resistance of its built-in thermistor and sends a signal to the air conditioning amplifier assembly.
15. SMOG VENTILATION SENSOR (w/ Rear Air Conditioning System) The smog ventilation sensor detects harmful elements such as CO, HC and NOx present in the air outside of the vehicle. The sensor outputs a signal to the air conditioning amplifier assembly. The sensitivity of the smog ventilation sensor can be adjusted. Adjustment can be done using the display and navigation module display.
16. AUTOMATIC LIGHT CONTROL SENSOR (SOLAR SENSOR) The automatic light control sensor (solar sensor) consists of a photo diode, 2 amplifier circuits for the solar sensor and a frequency converter circuit for the light control sensor. The automatic light control sensor (solar sensor) detects (in the form of changes in the current that flows through the built-in photo diode) the changes in the amount of sunlight from the LH and RH sides (2 directions) and outputs these sunlight intensity signals to the air conditioning amplifier assembly.

See also:
• DISASSEMBLY